56 



PRINCIPLES OP VETERINARY SCIENCE 



ing in the brain. When they are cut or interfered with the 

 muscle becomes paralyzed. 



Blood Supply.— A plentiful supply of blood is furnished through 

 the arteries of each muscle and is removed through the corre- 

 sponding veins (Fig. 12). 



Arrangement. — Muscles are arranged in groups of two, one 

 group acts in opposition or is antagonistic to the other. The 

 effectiveness of this arrangement is seen in the precision of 

 locomotion. 



Fig. 12. — Cross-section of left leg of horse, cut a little above middle: a, 

 Tibia; b, fibula; d, I, m, tendons of muscles; c, e, /, g, h, i, k, n, fleshy portions of 

 muscles; o, skin; p, s, w, arteries; v, :r, veins; q, q', r, t, v, y, nerves. (Ellenbergei 

 in Leisering's Atlas.) 



Accessory Structures. — To facilitate the play of a muscle or 

 tendon over bony prominences bursse and tendon sheaths are 

 provided. Bursa are small sacs filled with a fluid which resem- 

 bles synovia. They form pads to prevent friction. The tendon 

 sheaths are elongated, closed sacs containing serous fluid. They 

 are folded completely around the tendons, as the diagram (Fig. 

 13) shows. 



Names. — Each skeletal muscle has a name. Names of mus- 

 cles have been handed down from the earlier anatomists, who 



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